This invention relates to a separation method and apparatus, and has been devised, in particular, to provide a method of, and apparatus for, separating components situated down a drilled well.
In the development of oil wells, and in intervention operations, coiled tubing is used extensively to deploy a variety of tools down the well, and it is now becoming commonplace to run single or multi-cored armoured electrical cable within such tubing.
As the depth of wells increase, along with the complexity of the wells and the varying configurations of the various tools, the danger of a tool becoming stuck somewhere in a well becomes greater. The consequences of a tool becoming stuck in a well are potentially costly and may include loss of, or damage to, the downhole tool, the coiled tubing, and/or the well itself.
Thus, in the event of a tool becoming stuck in a well, it is desirable to be able to separate the tool from the tubing, in a controlled way, using a purpose built release mechanism.
Release mechanisms exist in various forms, operated variously by pressure applied through the coiled tubing, or by direct pull. However such existing mechanisms tend to restrict the scope of operations of the equipment. For example, in the case of direct pull operated release, the design maximum loads expected in normal execution of a job must fall below the separation load of the release mechanism by a considerable safety margin, to avoid unwanted release. In the case of a pressure operated release, operations which involve pumping a fluid through the coiled tubing (e.g. lifting or killing the well) must be closely monitored to ensure that the differential pressure created in the tube, by pumping, does not reach that at which disconnection will occur. This increases the time taken for the pumping operation.
It is an object of the present invention to provide a separation method and apparatus which will address the aforegoing problems or which will at least provide a useful choice.
According to one aspect of the invention, there is provided separation apparatus operable to separate components positioned down a well, said apparatus including a substantially cylindrical body section able to withstand loads in tension, compression and torsion; and electrically operable release means operable to separate parts of said body section, said release means being operable independently of any supply of fluid under pressure to said or through said body and independently of any tension, compression or torsion loads applied to said body section, characterized in that the release means comprises a fusible metal component.
The invention also provides apparatus adapted to be connected to an end of a coiled tube and comprises a through-bore through said body section to allow fluid under pressure to be conveyed through said apparatus.
The apparatus is preferably constructed and arranged to receive fluid under pressure from the environment surrounding, said apparatus, when submerged down a well, to cause said parts to undergo relative displacement.
The invention also provides apparatus adapted to be connected to a wireline.
The invention also provides apparatus wherein the metal includes tin and/or bismuth.
Preferably said release means includes a release catch operable by the melting of the fusible metal element, after which parts of said body section may be displaced with respect to one another to effect separation. Whilst some form of mechanical biasing means may be provided to displace the parts of said body section with respect to one another, the apparatus is preferably constructed and arranged to receive fluid under pressure from the environment surrounding said apparatus, when submerged down a well, to cause said parts to undergo relative displacement.
Preferably said apparatus is as hereinafter described.
Many variations in the way the present invention might be performed will present themselves to those skilled in the art. The description which follows is intended only as an illustration and the absence of particular alternatives or variants should in no way be applied to limit the scope of the invention. Such description of specific elements as follows should also be interpreted as including equivalents whether existing now or in the future. The scope of the invention should be determined solely by the appended claims.